Rod maker, method for operating the same and air conveyor system

ABSTRACT

A method of operating a rod maker for tobacco processing that includes sifting a tobacco flow in a chamber of the rod maker with a first air flow to separate tobacco ribs from the tobacco flow and conveying the sifted tobacco flow in the chamber by at least one of the first air flow and a second air flow. Moreover, the method includes conveying air out of the chamber via a third air flow and a fourth air flow, where a sum of an air throughput of the third air flow and the fourth air flow is substantially constant, irrespective of a productive capacity of the rod maker. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of GermanPatent Application No. 10 2004 007 841.6, filed on Feb. 17, 2004, thedisclosure of which is expressly incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for operating a rod maker (rod-makingmachine) for tobacco processing, in which a tobacco flow is sifted in achamber of the rod maker by a first air flow so that tobacco ribs areseparated from the tobacco flow, in which the sifted tobacco flow isconveyed in the chamber by the first and/or a second air flow, in whicha third and a fourth air flow are provided which convey air out of thechamber. The invention further relates to a rod maker of the tobaccoprocessing industry comprising a tobacco sifter, a suction rod conveyorand a device for conveying tobacco to the suction rod conveyor, in whichthe device for conveying tobacco defines a chamber, in which an air flowfor sifting and for conveying can be introduced into the chamber.

The invention finally relates to an air conveyor system for a rod makerof the tobacco processing industry, including a circulation fan and asuction fan, in which air can be conveyed by the circulation fan into achamber in which a tobacco flow can be sifted and conveyed in particularby the conveyed air, and where the suction fan is connected to thechamber, and air can be suctioned out of the chamber.

2. Discussion of Background Information

A corresponding method, a corresponding rod maker and a correspondingair conveyor system is known from EP 0 727 156 A1. A corresponding rodmaker is sold by the applicant under the name Protos 100.

However, with such a method, such a rod maker and such an air conveyorsystem, the effect occurs that the rib discharge from the tobacco flowto be sifted changes with the productive capacity of the rod maker.Thus, e.g., when the productive capacity is cut back, more tobacco issifted out, which leads to a deterioration of the efficiency of themethod and of the rod maker. Ultimately, this means the cigarettescorrespondingly produced have different properties.

SUMMARY OF THE INVENTION

In contrast, an aspect of the invention is to disclose a method foroperating a rod maker, a rod maker, and an air conveyor system for a rodmaker of the tobacco processing industry by which it is possible toproduce qualitatively uniform cigarette rods.

This aspect is attained with a method for operating a rod maker of thetobacco processing industry, in which a tobacco flow is sifted in achamber of the rod maker by a first air flow so that tobacco ribs areseparated from the tobacco flow, in which the sifted tobacco flow isconveyed in the chamber by the first and/or a second air flow, in whicha third and a fourth air flow are provided which convey air out of thechamber, that is further developed in that the sum of the air throughputof the third and fourth air flow is essentially constant irrespective ofthe productive capacity of the rod maker.

Within the scope of the invention, the term productive capacity means inparticular the speed of a rod formed from the sifted tobacco flow or alength of a cigarette rod per time unit. Within the scope of theinvention, the chamber is in particular a chamber in the rod maker whichcomprises a rolling chamber, a fluidized bed chamber, and a chamber inwhich a tobacco flow is sifted. The tobacco sifter can be a pre-sifter.The tobacco sifter can also comprise a post-sifter.

Furthermore, within the scope of the invention the term air throughputmeans the conveyed quantity of air per time unit or the conveyed airvolume per time unit.

By keeping the sum of the air throughput of the third and fourth airflow to an essentially constant value, irrespective of the productivecapacity of the rod maker, it is possible to influence the air pressurein the chamber such that a uniform sifting of the tobacco flow isrendered possible. The lower the productive capacity of the rod maker,the faster the suction belt of the suction rod conveyor, which can alsobe a suction belt conveyor within the scope of the invention, seals upby the application of tobacco so that less air in the form of the thirdair flow is carried away out of the chamber via the suction rodconveyor. The air throughput conveyed out of the chamber in the form ofthe fourth air flow should then be increased accordingly so that the airspeed at the sifter, comprising a pre-sifter and optionally apost-sifter, does not change too much and preferably remains constant sothat the rib discharge from the tobacco flow also remains constant. Thiseffect occurs essentially because the pressure in the chamber remainsessentially constant so that the air speed at the sifter does not haveto be changed. The sum of the air throughputs of the third and fourthair flow is kept constant automatically or when the rod maker isrunning.

If an air distributor is arranged upstream of the chamber, where air isdischarged from the air distributor into the surroundings, aparticularly effective and simple opportunity is provided to change theair throughput conveyed out of the chamber by the fourth air flow. Thefirst, second and fourth air flows are usually part of the circulatingair system that is driven by a circulation fan. In the event that air isreleased from the air distributor into the surroundings, and the airdistributor is also part of the circulating air system and is arrangedbetween the circulation fan and the chamber, the circulation fan conveysa greater air quantity due to the smaller pressure difference betweeninlet and outlet, i.e., the air throughput increases. The air throughputsuctioned out of the chamber is thus automatically increased.

The air distributor can also be an air pipe with a branch pipe.Furthermore, air can be released from the air distributor into thesurroundings via another air pipe. Preferably, the air throughputreleased into the surroundings is changed. If a throttle flap isadjusted in a discharge pipe of the air distributor to change thereleased air throughput, a particularly cost-effective implementation ofthe method is possible. Within the scope of the invention, the dischargepipe can also be a release pipe and is in particular a diffuser or endsin a diffuser.

Preferably an essentially constant pressure is established in thechamber. In this connection, the chamber comprises in particular therolling chamber or fluidized bed chamber of the rod maker.

Preferably the air throughput of the fourth air flow conveyed out of thechamber is controlled or regulated. The control or regulation can occurcontinuously so that the productive capacity of the rod maker can alsobe changed continuously without the quality of the cigarette rodproduced being impaired. To this end, e.g., the air pressure in thechamber is measured and preferably in the area of the sifter or in therolling chamber. If the control occurs progressively, e.g., bypredetermined positions of the throttle flap, a particularlycost-effective process control is possible.

The aspect is further attained through a rod maker of the tobaccoprocessing industry comprising a tobacco sifter, a suction rod conveyorand a device for conveying tobacco to the suction rod conveyor, in whichthe device for conveying tobacco defines a chamber, in which an air flowcan be introduced into the chamber for sifting and conveying, in whichthe air throughput removed from the chamber is essentially constantirrespective of the productive capacity of the rod maker. According tothe invention this occurs automatically or when the machine is running.

Within the scope of the invention the term a device for conveyingtobacco includes an apparatus for conveying and/or guiding an air flowor several air flows by which tobacco can be moved. Furthermore, thedevice for conveying tobacco also comprises, e.g., drop ducts, afluidized bed, and other devices in a rod maker of the tobaccoprocessing industry.

Preferably an air distributor is arranged upstream of the chamber in theconveyor direction of the air flow, and the air distributor features anoutlet into the surroundings. A particularly precise conveying of airflow in the rod maker is thus possible. If the air throughput that canbe released into the surroundings is variable, a particularly effectiveand simple opportunity is realized of achieving a uniform tobacco rodeven with differing productive capacities of the rod maker. Aparticularly cost-effective implementation is provided by providing athrottle flap in the outlet.

Preferably a pressure sensor is provided in the chamber. By the pressuresensor, it is easily possible to implement a control or regulation ofthe air throughput that can be released into the surroundings. To thisend, the pressure sensor is preferably arranged in the area of thesifter or in the rolling chamber of the fluidized bed. A control orregulating device is provided to control or regulate the air throughputthat can be released into the surroundings. In a particularly preferredembodiment of the invention the control or regulation is renderedpossible continuously. It is thus possible to change the productivecapacity of the rod maker continuously as well without the quality ofthe endless rod suffering. If the control or regulation is renderedpossible progressively, predetermined productive capacities can beestablished where the endless rods produced with these productivecapacities in any case feature a high quality. An interpolation can takeplace between the corresponding productive capacities whereby acorrespondingly high quality of the endless rod is rendered possibleeven with no predetermined productive capacities. Preferably, at leasttwo throttle flap positions can be predetermined. Through this, aparticularly simple and cost-effective realization of the rod maker isprovided, especially as in operation two different productive capacitiesare normally used by cigarette manufacturers in cigarette production orcigarette rod production.

The aspect is further attained through a rod maker of the tobaccoprocessing industry, including a tobacco sifter, a suction rod conveyorand a device for conveying tobacco to the suction rod conveyor, in whichthe device for conveying tobacco defines a chamber, in which an air flowfor sifting and for conveying can be introduced into the chamber, inwhich at least part of the air flow can be released into thesurroundings upstream of the chamber with respect to the conveyordirection of the air flow, in which the air throughput that can bereleased into the surroundings is dependent on the productive capacityof the rod maker. It is thus rendered possible in a simple manner forthe air throughput that can be conveyed out of the chamber by acirculating air system to be varied depending on the productive capacityof the rod maker, so that essentially a constant pressure can beachieved in the chamber and so that the tobacco sifter has an air flowavailable at an essentially constant speed.

Preferably the air throughput that can be released into the surroundingscan be increased at lower productive capacity. A particularly effectiveembodiment of the rod maker according to the invention is provided if anair distributor is arranged upstream of the chamber in the conveyordirection of the air flow, and the air distributor features an outletinto the surroundings. A cost-effective solution is given if a throttleflap is provided to change the air throughput that can be released intothe surroundings.

The aspect of the invention is finally attained through an air conveyorsystem for a rod maker of the tobacco processing industry comprising acirculation fan and a suction fan, in which air can be conveyed by thecirculation fan into a chamber in which a tobacco flow can be sifted andconveyed, in particular by the conveyed air, and in which the suctionfan is connected to the chamber, and air can be suctioned out of thechamber, in which the air throughput that can be conveyed out of thechamber is essentially constant irrespective of the productive capacityof the rod maker.

An air distributor is preferably arranged downstream of the circulationfan and upstream of the chamber. A particularly effective air guidanceis rendered possible in the air conveyor system if by releasing airupstream of the chamber it is made possible to keep constant the airthroughput that can be conveyed out of the chamber. It is expedient toprovide a throttle flap in a pipe discharging air into the surroundings.Preferably, an essentially constant pressure can be established in thechamber. To this end, e.g., a pressure sensor can be used in thechamber. The aspect can be attained very effectively if a control orregulating device is provided to control or regulate the air throughputreleased into the surroundings. The control or regulation preferablyoccurs continuously or progressively, and with the latter alternativetwo positions or three positions of the throttle flap are preferablyprovided or two or three predetermined air throughputs can bepredetermined.

Other exemplary embodiments and advantages of the present invention maybe ascertained by reviewing the present disclosure and the accompanyingdrawing.

One aspect of the invention includes a method of operating a rod makerfor tobacco processing that includes sifting a tobacco flow in a chamberof the rod maker with a first air flow to separate tobacco ribs from thetobacco flow and conveying the sifted tobacco flow in the chamber by atleast one of the first air flow and a second air flow. Moreover, themethod includes conveying air out of the chamber via a third air flowand a fourth air flow, where a sum of an air throughput of the third airflow and the fourth air flow is substantially constant, irrespective ofa productive capacity of the rod maker.

In a further aspect of the invention, an air distributor can be arrangedupstream of the chamber, and the method can further include dischargingair into the surroundings from the air distributor. Furthermore, themethod can include varying the air throughput discharged into thesurroundings. Additionally, the method can include adjusting a throttleflap in a discharge pipe of the air distributor to change the airthroughput discharged. The method can further include establishing anessentially constant pressure in the chamber. Moreover, the method caninclude one of controlling and regulating the air throughput of thethird air flow conveyed out of the chamber. Additionally, the one of thecontrolling and regulating can further include one of continuouslycontrolling and continuously regulating. Moreover, the method caninclude progressively controlling the air throughput. Furthermore, a rodmaker for tobacco processing can be structured and arranged to performthe above-noted method.

Yet another aspect of the invention includes a rod maker for tobaccoprocessing that includes a tobacco sifter, a suction rod conveyor, and adevice structured and arranged for conveying tobacco to the suction rodconveyor. Moreover, the device includes a chamber, structured andarranged to receive an air flow for sifting and for conveying.Additionally, an air throughput removed from the chamber issubstantially constant, irrespective of the productive capacity of therod maker.

In a further aspect of the invention, the rod maker can include an airdistributor, arranged upstream of the chamber in a conveying directionof the air flow, comprising a discharge arranged to discharge air intothe surroundings. Moreover, the air throughput dischargeable into thesurroundings can be variable. The rod maker can further include athrottle flap positioned in the discharge. Furthermore, the rod makercan include a pressure sensor positioned in the chamber. Additionally,the rod maker can include one of a controller and regulator structuredand arranged for one of controlling and regulating the air throughputdischargeable into the surroundings. Moreover, one of the controller andregulator are configured to operate continuously. Furthermore one of thecontroller and regulator are configured to operate progressively.

Another aspect of the invention includes a rod maker for tobaccoprocessing that includes a tobacco sifter, a suction rod conveyor, and adevice structured and arranged for conveying tobacco to the suction rodconveyor. The device including a chamber structured and arranged toreceive an air flow for sifting and for conveying the tobacco. Moreover,the rod maker includes at least part of the air flow is releasable intothe surroundings upstream of the chamber with respect to the conveyordirection of the air flow, and an air throughput releasable into thesurroundings is variable depending on the productive capacity of the rodmaker.

In a further aspect of the invention the air throughput releasable intothe surroundings can increase with lower productive capacity. Moreover,an air distributor can be arranged upstream of the chamber in theconveyor direction of the air flow, and the air distributor includes adischarge arranged to discharge air into the surroundings. Additionally,the rod maker can include a throttle flap structured and arranged forchanging the air throughput releasable into the surroundings.

Yet another aspect of the invention includes an air conveyor system fora rod maker for tobacco processing. The system includes a circulationfan structured and arranged for introducing conveying air into a chamberto sift and convey a tobacco flow, and a suction fan, connected to thechamber, operable to suction air out of the chamber. Moreover, an airthroughput conveyed out of the chamber is substantially constant,irrespective of the productive capacity of the rod maker.

In a further aspect of the invention the air conveyor system can furtherinclude an air distributor arranged downstream of the circulation fanand upstream of the chamber. Moreover, the air throughput conveyed outof the chamber can be kept constant by releasing air upstream of thechamber. Furthermore, the system can include a throttle flap positionedin a pipe to discharge air into the surroundings. Additionally, asubstantially constant pressure can be generatable in the chamber.Moreover, the system can include one of a controller and a regulatorstructured and arranged to control or regulate the air throughputdischarged into the surroundings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention,in which like reference numerals represent similar parts throughout theseveral views of the drawings, and wherein:

FIG. 1 shows a diagrammatic representation of a rod maker in anembodiment according to the invention; and

FIG. 2 shows a diagrammatic representation of a rod maker air systemaccording to the invention,

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present invention onlyand are presented in the cause of providing what is believed to be themost useful and readily understood description of the principles andconceptual aspects of the present invention. In this regard, no attemptis made to show structural details of the present invention in moredetail than is necessary for the fundamental understanding of thepresent invention, the description taken with the drawings makingapparent to those skilled in the art how the several forms of thepresent invention may be embodied in practice.

FIG. 1 shows diagrammatically a rod maker 10 according to the invention.In the rod maker 10 several elements represented by a dotted line willbe explained below.

Tobacco is conveyed from a tobacco supply by a steep wall conveyor 11 toa retaining duct 12. Tobacco is removed from the retaining duct 12 by aremoval roll 13 and a beater roll 14 and delivered essentially separatedto a duct 15. A tobacco flow 38, directed downwards, forms in the duct15.

The tobacco flow 38 reaches the area of a sifter, and in particular, anarea of a pre-sifter 16 in which the tobacco flow 38 is pre-sifted by anair flow from an air flow pipe 32 ₁, such that the light tobacco flowcomponents are conveyed in the direction of a fluidized bed 18 and theheavy tobacco flow components, essentially tobacco ribs, fall throughdownwards. The tobacco flow components falling through downwards arepost-sifted in a post-sifter 17. Sifting tobacco is known per se so nofurther details about sifting need to be addressed.

By the air flow, which is directed from an air flow pipe 32 ₂ of thepost-sifter onto the tobacco flow 38′, and by the air flow from thepre-sifter 16, the sifted tobacco flow 38′ reaches the fluidized bed 18in which through further air flow pipes 32 ₃ air flows throughcorresponding nozzles, e.g., Coanda nozzles, the sifted tobacco flow 38′is conveyed further in the direction of the suction rod conveyor 19.

The ribs that have been sifted out arrive via the rib duct 25 in thedirection of a shaking trough 26 out of which smaller tobacco componentsare shaken so that essentially only ribs are carried away.

Some air flow pipes 32 ₁, 32 ₂, 32 ₃, 32 ₄, 32 ₅, 32 ₆, 32 ₇, 32 ₈, 32₉, 32 ₁₀, 32 ₁₁, and 32 ₁₂ are provided in the rod maker according tothe invention in order to convey the corresponding air flows.

A circulating air system 44 is provided that includes a circulation fan24. The circulation fan 24 conveys compressed air controlled orregulated via a throttle flap 23 into an air distributor 21 from whichcompressed air is guided via a throttle flap 22 to the pre-sifter 16.Furthermore, the air distributor 21 guides compressed air to thepost-sifter 17 and via further pipes 32 ₃ to the nozzles in thefluidized bed 18. The air is then guided out of the rolling chamber 20via an air pipe 32 ₄ to a dust-extraction cyclone that separates the airfrom tobacco dust conveyed with the air. Another part is conveyed viapipes 32 ₅ to the air circulation of the suction rod conveyor fan 27.

A part of the corresponding air flow or air throughput controlled orregulated via the throttle flap 23 is fed to the circulation fan again.Furthermore, an air flow is guided out of the rolling chamber 20 by thesuction rod conveyor 19 and fed via two throttle flaps 28 and 29 to asuction rod conveyor fan 27. The throttle flap 28 is used to shut offvacuum intake air when the suction rod conveyor is lifted. The throttleflap 29 is used to reduce the air capacity of the suction rod conveyorfan 27 when the rod maker is stopped.

Furthermore, the suction rod conveyor fan 27 draws air out of thesurroundings via another pipe 32 ₆ that opens between the throttle flap29 and the suction rod conveyor fan 27. Compressed air is blown to theair control center from the suction rod conveyor fan 27, and thethrottle flap 31 is provided to establish the vacuum in the suction rodconveyor and the throttle flap 30 establishes a pressureless transitionsuch that the amount of air suctioned off from the control center issomewhat greater than the amount of air discharged from the machine.This thus compensates for the pressure fluctuations of the central dustextraction and the heat produced is discharged at least partially fromthe machine. Finally, a further pressure line 32 ₇ leads from theshaking trough 26 into the discharge pipe from the suction rod conveyorfan 27 so that an air flow is entrained there too.

With falling productive capacity, with rod makers of the prior art orwith corresponding methods for operating a rod maker of the tobaccoprocessing industry, it has now transpired that the rib discharge ortobacco discharge or the percentage rib discharge has increased withfalling productive capacity. It has hereby been realized that withfalling productive capacity the increasing rolling chamber pressure orthe increasing pressure in the area of the chamber around the sifter,the pre-sifter 16 and the post-sifter 17, has a restricting impact onthe respective sifters 16 and 17 so that the rib quantity or the siftedout rib quantity or tobacco quantity is increased.

It was now determined according to the invention that by keepingconstant the sum of the air throughput conveyed out of the rollingchamber or out of the sifting chamber, the percentage rib discharge orthe percentage tobacco discharge can be kept constant, even with reducedproductive capacity. This occurs, e.g., according to the exemplaryembodiment of FIG. 1 through automatic adjustment of the throttle flap34 through which a corresponding air throughput is guided via a pipe 32′to a diffuser 35, through which a corresponding air throughput isreleased into the surroundings.

The automatic adjustment of the throttle flap 34 for the diffuser 35 canpreferably occur through a compressed-air cylinder. Two positions are inparticular suitable for this, in particular with stops that can beprecisely adjusted, if two productive capacities of the machine areused. Thus, for example, the productive capacities of 10,000 cigarettesper minute and 6,000 or 4,000 cigarettes per minute can be used. Withreduced productive capacity an increased air throughput is suctioned outof the rolling chamber via the circulation fan 24, which is achieved bya greater air throughput being released into the surroundings from theair distributor 21 via the pipe 32′. By releasing compressed air via thediffuser or the pipe 32′ into the surroundings, there is a smallerdifference in pressure between the inlet and the outlet of thecirculation fan so that the air throughput through the circulation fanis increased, which ultimately leads to an increase in the airthroughput of the air flow discharged from the rolling chamber, whichessentially compensates for the reduced air throughput with reducedproductive capacity through the suction rod conveyor.

The productive capacity of the rod makers is, e.g., restricted if thereservoir that lies between the rod maker and a corresponding packingmachine is full. In this respect it actually also happens in theproduction of cigarettes and the subsequent packing that the machinecapacity or productive capacity has to be throttled. This can happen,e.g., when the packing machine comes to a stop, and the rod maker isstill functioning properly.

FIG. 2 shows a diagrammatic representation of the air system of a rodmaker according to the invention in another aspect. Compressed air isguided to the air distributor 21 via the circulation fan 24. To thisend, an air flow 320 is provided. An air flow 321 that can be controlledor regulated via a throttle flap 45 is guided from the air distributor21 to the pre-sifter. A pressure of, e.g., in the range of between 10and 80 mbar prevails in the air distributor 21, Furthermore, an air flow322 is guided to a post-sifter nozzle from the air distributor 21.Moreover, an air flow 323 that divides into three air flows is fed tothe fluidized bed nozzles.

Air flows 326, 327 from the atmosphere also arrive in the rollingchamber in the area of the pre-sifter. The air distributor 21 alsoguides an air flow 337 to the suctioning off of the ribs. Thecorrespondingly discharged ribs arrive at a shaking trough 26 with thegravitational force and an air flow 336 and are then brought to a ribstorage 37 via an air flow 332. Through the air flow 322 guided from theair distributor 21 to the post-sifter, an air flow 335 also arises fromthe atmosphere, which air flow changes into an air flow 324. Moreover,from the rolling chamber 36 an air flow 330 reaches the dust extractioncyclone 33 from which an air flow 334 that can be controlled orregulated with a throttle flap is guided back to the circulation fan 24again.

The air distributor 21 also discharges an air flow 325 that can becontrolled or regulated via the throttle flap 34. This air flow 325 endsin a diffuser 35 and subsequently in the surrounding air. The airthroughput conveyed out of the rolling chamber 36 via the air flow 330is controlled or regulated via the air flow 325. A regulation is takingplace in the exemplary embodiment of FIG. 2. In this case, a regulatingparameter is the rolling chamber pressure that is measured by a pressuresensor 42, the signal of which is fed via a measurement line 41 to acontrol or regulating device 40.

The control or regulating device 40 controls or regulates the throttleflap 34 via a control line 43. A continuous regulation can take place,as indicated in FIG. 2, or the productive capacity can be set in thecontrol or regulating device 40 from another location in the machine sothat a corresponding control of the position of the throttle flap 34 isrendered possible. The rolling chamber pressure changes because the airflow 340 discharged from the rolling chamber 36 changes its throughputwith different productive capacities of the rod maker, since the suctioncapacity of the suction belt conveyor 19 is also reduced with reducedproductive capacity of the rod maker.

Due to the suctioning of tobacco or the vacuum in the suction rodconveyor 19 an air flow 328 is also marked that originates from theatmosphere. The pressure in the suction rod conveyor is in the range of−80 mbar. An air flow 329 is guided from the suction rod conveyor to thesuction fan. The suction fan or suction rod conveyor fan 27 works at acapacity of 7.5 kW and guides in the air flow 333 an air throughput tothe control center that features an essentially constant air throughputduring production and during stoppage. Accordingly, another air flowleads to the control center from the rib storage 37.

Furthermore, an air flow 338 is provided in order to introduce dust intothe system on a return conveyor belt. Another air flow 339 reaches thesuction rod conveyor fan 27 from the flute gear. The circulating airsystem and suction air system are connected to one another via the airflows 331.

The circulation fan works at a capacity of approximately 5.5 kW. Thefluidized bed chamber has a pressure of approximately 0 mbar. A controlof the throttle flap 34 for the so-called diffuser air 325 with two ormore discrete positions represents a very simple and cost-effectivesolution. A regulation of the position of the throttle flap 34 to aconstant rolling chamber pressure leads to a stability of the functionof the sifter at all productive capacities.

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to an exemplary embodiment, it is understood that thewords which have been used herein are words of description andillustration, rather than words of limitation. Changes may be made,within the purview of the appended claims, as presently stated and asamended, without departing from the scope and spirit of the presentinvention in its aspects. Although the present invention has beendescribed herein with reference to particular means, materials andembodiments, the present invention is not intended to be limited to theparticulars disclosed herein; rather, the present invention extends toall functionally equivalent structures, methods and uses, such as arewithin the scope of the appended claims.

List of Reference Numbers 10 Rod maker 11 Steep wall conveyor 12Retaining duct 13 Removal roll 14 Beater roll 15 Duct 16 Pre-sifter 17Post-sifter 18 Fluidized bed 19 Suction rod conveyor 20 Rolling chamber21 Air distributor 22 Throttle flap 23 Throttle flap 24 Circulation fan25 Rib duct 26 Shaking trough 27 Suction rod conveyor fan 28 Throttleflap 29 Throttle flap 30 Throttle flap 31 Throttle flap  32₁-32₁₂ Airflow pipe  32′ Discharge pipe 33 Dust-removal cyclone 34 Throttle flap35 Diffuser 36 Fluidized bed chamber 37 Rib storage 38 Tobacco flow  38′Sifted tobacco flow 39 Tobacco ribs 40 Control or regulator device 41Measurement line 42 Pressure sensor 43 Control line 44 Circulating AirSystem 45 Throttle flap 320-340 Air flow

1. A method of operating a rod maker for tobacco processing comprising:sifting a tobacco flow in a chamber of the rod maker with a first airflow to separate tobacco ribs from the tobacco flow; conveying thesifted tobacco flow in the chamber by at least one of the first air flowand a second air flow; and conveying air out of the chamber via a thirdair flow and a fourth air flow, wherein a sum of an air throughput ofthe third air flow and the fourth air flow is substantially constant,irrespective of a productive capacity of the rod maker.
 2. The methodaccording to claim 1, wherein an air distributor is arranged upstream ofthe chamber, and the method further comprises: discharging air into thesurroundings from the air distributor.
 3. The method according to claim2, further comprising: varying the air throughput discharged into thesurroundings.
 4. The method according to claim 3, further comprising:adjusting a throttle flap in a discharge pipe of the air distributor tochange the air throughput discharged.
 5. The method according to claim1, further comprising: establishing an essentially constant pressure inthe chamber.
 6. The method according to claim 1, further comprising: oneof controlling and regulating the air throughput of the third air flowconveyed out of the chamber.
 7. The method according to claim 6, whereinthe one of the controlling and regulating further comprises one ofcontinuously controlling and continuously regulating.
 8. The methodaccording to claim 6, further comprising: progressively controlling theair throughput.
 9. A rod maker for tobacco processing structured andarranged to perform the method of claim
 1. 10. A rod maker for tobaccoprocessing comprising: a tobacco sifter; a suction rod conveyor; and adevice structured and arranged for conveying tobacco to the suction rodconveyor, the device comprising a chamber structured and arranged toreceive an air flow for sifting and for conveying, wherein an airthroughput removed from the chamber is substantially constant,irrespective of the productive capacity of the rod maker.
 11. The rodmaker according to claim 10, further comprising: an air distributor,arranged upstream of the chamber in a conveying direction of the airflow, comprising a discharge arranged to discharge air into thesurroundings.
 12. The rod maker according to claim 11, wherein the airthroughput dischargeable into the surroundings is variable.
 13. The rodmaker according to claim 11, further comprising: a throttle flappositioned in the discharge.
 14. The rod maker according to claim 10further comprising: a pressure sensor positioned in the chamber.
 15. Therod maker according to claim 11, further comprising: one of a controllerand regulator structured and arranged for one of controlling andregulating the air throughput dischargeable into the surroundings. 16.The rod maker according to claim 15, wherein one of the controller andregulator are configured to operate continuously.
 17. The rod makeraccording to claim 15, wherein one of the controller and regulator areconfigured to operate progressively.
 18. A rod maker for tobaccoprocessing comprising a tobacco sifter; a suction rod conveyor; and adevice structured and arranged for conveying tobacco to the suction rodconveyor, the device comprising a chamber structured and arranged toreceive an air flow for sifting and for conveying the tobacco, whereinat least part of the air flow is releasable into the surroundingsupstream of the chamber with respect to the conveyor direction of theair flow, and an air throughput releasable into the surroundings isvariable depending on the productive capacity of the rod maker.
 19. Therod maker according to claim 18, wherein the air throughput releasableinto the surroundings increases with lower productive capacity.
 20. Therod maker according to claim 18, wherein an air distributor is arrangedupstream of the chamber in the conveyor direction of the air flow, andthe air distributor comprises a discharge arranged to discharge air intothe surroundings.
 21. The rod maker according to claim 18, furthercomprising: a throttle flap structured and arranged for changing the airthroughput releasable into the surroundings.
 22. An air conveyor systemfor a rod maker for tobacco processing, comprising: a circulation fanstructured and arranged for introducing conveying air into a chamber tosift and convey a tobacco flow; and a suction fan, connected to thechamber, operable to suction air out of the chamber, wherein an airthroughput conveyed out of the chamber is substantially constant,irrespective of the productive capacity of the rod maker.
 23. The airconveyor system according to claim 22, further comprising: an airdistributor arranged downstream of the circulation fan and upstream ofthe chamber.
 24. The air conveyor system according to claim 22, whereinthe air throughput conveyed out of the chamber is kept constant byreleasing air upstream of the chamber.
 25. The air conveyor systemaccording to claim 23, further comprising: a throttle flap positioned ina pipe to discharge air into the surroundings.
 26. The air conveyorsystem according to claim 22, wherein a substantially constant pressureis generatable in the chamber.
 27. The air conveyor system according toclaim 22, further comprising: one of a controller and a regulatorstructured and arranged to control or regulate the air throughputdischarged into the surroundings.